Nomadics, Inc. proposes to use amplifying fluorescent polymer (AFP) nanoparticles to improve the sensitivity of nucleic acid hybridization assays by up to 5 orders of magnitude. This will directly impact gene expression studies by improving sensitivity and enabling quantitative comparison with reference samples. Rapid energy migration of the excited state along the conjugated polymer backbone of fluorescent polymers amplifies the optical signature of a molecular quenching or FRET event. Amplification is further enhanced by three-dimensional energy migration in a condensed solid. Nomadics has developed materials and methods for the facile preparation of aqueous nanoparticle dispersions of fluorescent poly(phenylene ethynylene) polymers. This will enable application of these materials for the detection of nucleic acid hybridization in homogeneous assays and array formats. In this Phase I effort, Nomadics will expand our techniques for the fabrication of fluorescent polymer nanoparticles; define methods for preparing nanoparticle-nucleic acid conjugates; demonstrate transduction of the nanoparticte fluorescence via nucleic acid hybridization; and evaluate the sensitivity potential of nanoparticles in a microarray format. Phase II will develop quantitative microarray-based systems for gene expression studies that leverage the large optical signals generated by AFP nanoparticles. [unreadable] [unreadable]